Fibroblast growth factor 23 in chronic kidney disease: what is its role in cardiovascular disease?

Assessment of atherosclerosis and endothelial dysfunction risk factors in patients with primary glomerulonephritis

INTRODUCTION

Glomerulonephritis are the third cause of chronic kidney disease (CKD) requiring dialysis in Brazil. Mineral and bone disorder (MBD) is one of the complications of CKD and is already present in the early stages. Assessment of carotid intima-media thickness (CIMT) and flow-mediated vasodilatation (FMV) are non-invasive ways of assessing cardiovascular risk.

HYPOTHESIS

Patients with primary glomerulonephritis (PG) have high prevalence of atherosclerosis and endothelial dysfunction, not fully explained by traditional risk factors, but probably influenced by the early onset of MBD.

OBJECTIVE

To evaluate the main markers of atherosclerosis in patients with PG.

METHOD

Clinical, observational, cross-sectional and controlled study. Patients with PG were included and those under 18 years of age, pregnants, those with less than three months of follow-up and those with secondary glomerulonephritis were excluded. Those who, at the time of exams collection, had proteinuria higher than 6 grams/24 hours and using prednisone at doses higher than 0.2 mg/kg/day were also excluded.

RESULTS

95 patients were included, 88 collected the exams, 1 was excluded and 23 did not undergo the ultrasound scan. Patients with PG had a higher mean CIMT compared to controls (0.66 versus 0.60), p = 0.003. After multivariate analysis, age and values for systolic blood pressure (SBP), FMV and GFR (p = 0.02); and FMV and serum uric acid (p = 0.048) remained statistically relevant.

DISCUSSION AND CONCLUSION

The higher cardiovascular risk in patients with PG was not explained by early MBD. Randomized and multicentric clinical studies are necessary to better assess this hypothesis.

Avaliação dos fatores de risco de aterosclerose e disfunção endotelial em pacientes com glomerulopatias primárias

Resumo Introdução: Glomerulopatias são a terceira causa de doença renal crônica (DRC) com necessidade de diálise no Brasil. Distúrbio mineral e ósseo (DMO) é uma das complicações da DRC e está presente já nos estágios iniciais. A avaliação da espessura médio-intimal de carótidas (EMIC) e da vasodilatação fluxo-mediada (VFM) são maneiras não invasivas de avaliação do risco cardiovascular. Hipótese: Pacientes com glomerulopatias primárias (GP) apresentam alta prevalência de aterosclerose e disfunção endotelial, não explicada totalmente pelos fatores de risco tradicionais, mas provavelmente influenciada pela instalação precoce do DMO. Objetivo: Avaliar os principais marcadores de aterosclerose em pacientes com GP. Método: Estudo clínico, observacional, transversal e controlado. Foram incluídos portadores de GP e excluídos menores de 18 anos, gestantes, menos de três meses de seguimento e os com glomerulopatia secundária. Também foram excluídos aqueles que, no momento da coleta, apresentavam proteinúria maior que 6 gramas/24 horas e uso de prednisona em doses superiores a 0,2 mg/kg/dia. Resultados: 95 pacientes foram incluídos, 88 colheram os exames, 1 foi excluído e 23 não realizaram a ultrassonografia. Os pacientes com GP apresentaram maior EMIC média em relação ao controle (0,66 versus 0,60), p = 0,003. Após análise multivariada, mantiveram relevância estatística a idade e os valores de pressão arterial sistólica (PAS), VFM e TFG (p = 0,02) e VFM e ácido úrico sérico (p = 0,048). Discussão e conclusão: Pacientes com GP apresentaram maior risco cardiovascular, entretanto esse risco não foi explicitado pelo DMO precoce. Estudos clínicos randomizados e multicêntricos são necessários para melhor determinação dessa hipótese.

Fibroblast Growth Factor 23 Level and Cardiovascular Parameters in Children with Chronic Kidney Disease

OBJECTIVE

To find out the serum fibroblast growth factor 23 (FGF-23) levels in different grades of CKD, and the prevalence of abnormal left ventricular mass index (LVMI), carotid intima-medial thickness (cIMT), and central pulse wave velocity (cPWV) and the risk factors including FGF-23 for these abnormalities.

METHODS

Fifty-nine patients of CKD with G2 to G5, aged 2-18 y were included. The LVMI, cIMT, and cPWV were measured using standard techniques, and serum intact FGF-23 levels were estimated at enrollment.

RESULTS

Median FGF-23 levels were significantly raised in all the grades of CKD than controls (p < 0.001), and also in G4 and G5 in comparison to G2&3 and in G5D than G5. Increased LVMI in 42 (71.2%), elevated cIMT in 30 (57.7%), and cPWV in 14 (26.9%) patients were found. The FGF-23 showed significant negative correlation with eGFRcr and positive with serum iPTH, phosphate and alkaline phosphatase levels, but had no correlations with LVMI, cIMT SDS, and cPWV SDS. Only systolic BP SDS (odds ratio 1.5, 95% CI 1.008-2.231, p = 0.046) was observed as a significant predictor for increased cIMT, while no variables had any association with abnormal LVMI and cPWV.

CONCLUSIONS

Serum FGF-23 showed higher levels with increasing grades of CKD, but no significant association with cardiovascular parameters. Systolic BP SDS was found as a significant risk factor for increased cIMT in children with CKD.

Relationship between serum growth differentiation factor 15, fibroblast growth factor-23 and risk of atrial fibrillation: A systematic review and meta-analysis

Background and objective

Growth differentiation factor-15 (GDF-15) and fibroblast growth factor-23 (FGF-23) are considered predictors of the incidence of cardiovascular diseases. The present meta-analysis aimed to elucidate the associations between GDF-15 and FGF-23 in the risk of atrial fibrillation (AF).

Methods

An electronic search was conducted in the Cochrane Library, PubMed, and Embase databases from inception until February 27, 2021. The study protocol was registered in the PROSPERO database (CRD42020182226).

Results

In total, 15 studies that enrolled 36,017 participants were included. Both serum FGF-23 and GDF-15 were elevated in patients with AF. Analysis of categorical variables showed higher serum FGF-23 levels were associated with an increased risk of AF [relative risk (RR) = 1.28, 95% confidence interval (CI): 1.05–1.56]. In contrast, this association was not found with GDF-15 (RR = 0.91, 95% CI: 0.20–4.04). In dose-response analysis, a linear positive association was noted between serum FGF-23 levels and the risk of AF (P nonlinear = 0.9507), with a RR elevation of 7% for every 20 pg/ml increase in the serum FGF-23 levels (95% CI: 1.02–1.13). No remarkable relationship was found between serum GDF-15 levels and the risk of AF, and the overall RR for the association between a 100 ng/L increment in GDF-15 levels and AF was 1.01 (95% CI: 0.998–1.02).

Conclusion

Our study showed a positive linear correlation between serum FGF-23 levels and the risk of AF. However, no significant association was found between GDF-15 and the risk of AF. Further studies are warranted to clarify whether serum FGF-23 levels may be considered in predicting the risk of AF.

Systematic Review Registration:http:www.york.ac.uk/inst/crd, identifier CRD42020182226.

Klotho in kidney diseases: A crosstalk between the renin-angiotensin system and endoplasmic reticulum stress

Klotho is a transmembrane anti-ageing protein that exists in three forms, i.e., α-Klotho, β-Klotho, and γ-Klotho with distinct organ-specific expression and functions in the body. Here we focus on α-Klotho (mentioned as 'Klotho' only), abundantly expressed by the distal and proximal convoluted tubules of the kidney. Significant decline in systemic and renal Klotho level is a new hallmark for kidney disease progression. Emerging research portrays Klotho as a promising diagnostic as well as a therapeutic target for diabetic and non-diabetic kidney disease. Even so, the underlying mechanisms of Klotho regulation and the strategies to restore its systemic as well as the renal level are still lacking. Angiotensin-converting enzyme inhibitors (ACEi) and/or angiotensin receptor blockers (ARBs) are the current standard of care for kidney diseases where the molecular mechanisms for their nephroprotective action are still ambiguous. Moreover, endoplasmic reticulum stress (ER stress) also plays a crucial role in kidney disease progression. Few studies have claimed that RAAS has a direct relation with ER stress generation and vice versa in kidney disease. Interestingly, RAAS and ER stress modulation is associated with Klotho regulation in kidney disease. Here we focus on how the RAAS and ER stress connects with Klotho regulation in kidney disease. We also discuss Klotho and ER stress in an alliance with the concept of hemodynamic and metabolic overload in kidney disease. In addition, we highlight novel approaches to implement Klotho as a therapeutic target via RAAS and ER stress modulation for the treatment of diabetic and non-diabetic kidney disease.